Flexible circuits are widely used in the area of consumer electronics due to the substantial reduction in the thickness and size of the resulting product. In particular, flexible circuits are currently being used in the construction of disc drives and flat panel displays for consumer products such as television monitors, computer monitors, and mobile telephone monitors. As electronic technology continues to progress, consumers are increasingly interested in thinner and more compact electrical products. The use of flexible circuits in the construction of television, computer, and phone monitors allows the thickness and weight of the panels to be substantially reduced, providing a more compact product.
When electrical components are used in consumer electronics, care must be taken to prevent the product from igniting or shorting. Thus, to ensure consumer safety, the electrical components of all consumer electronics must pass Underwriters Laboratories (UL) registration, which provides fire protection testing and approval procedures. Additionally, to prevent fires and shorting of electrical components, flexible circuits should maintain their electrical resistance in relatively harsh environments, such as an 85% relative humidity and 85 degrees Celsius (° C.) environment. To meet these requirements, flexible circuits are typically covered with a protective covercoat to protect the flexible circuit from the external elements of the environment. The covercoat on the flexible circuit is desirably flame-resistant and moisture impervious, providing protection to the flexible circuit when exposed to a high humidity or high temperature environment. This protects against the electrical components of the product either igniting or shorting.
While some existing current covercoat compositions are capable of passing flame-resistance tests, most are not capable of passing electrical bias tests at high humidity and high temperatures. This is due to the fact that the covercoats tend to absorb moisture from the environment, causing the electrical resistance to break down over time. An example of a current covercoat composition being used is an epoxy-based covercoat. Epoxy-based covercoats are typically not capable of passing flame-resistance tests without the use of a halogen, such as a brominated flame retardant, and are typically not capable of passing electrical resistance tests at all, and therefore cannot be used to protect flexible circuits in consumer electronics. Additionally, current covercoat compositions typically include at least one chemical halogen, which can be environmentally unfriendly.